Storing Data Files in a File System

ABSTRACT

A mechanism is provided for storing data files in a file system. The file system provides a plurality of reference data files, where each reference data file in the plurality of data files represents a group of similar data files. The mechanism creates a new data file and associated the new data file with one reference data file in the plurality of data files thus defining an associated reference data file of the plurality of reference data files. The mechanism informs the file system about the association of the new data file with the associated reference data file. The mechanism compresses the new data file using the associated reference data file thereby forming a compressed data file. The mechanism stores the compressed data file together with information about the association of the new data file with the associated reference data file.

BACKGROUND

The present invention relates in general to data processing systems, andin particular, to a method and a system for storing data files in a filesystem.

Some types of applications have the characteristic of storing largenumbers highly redundant (similar) unstructured data objects (files) ina file system. One example is an application processing and storinggenomic sequence data of a large number of individuals of the samespecies. Such applications are being used more and more in the lifescience industry generating significant amount of data volume andstoring these as a plurality of files in file systems. In the case ofapplications for genomic sequence data the scanning speed of geneticsequencers increases exponentially with each new generation leading toeven more data hardly to be stored on storage devices for reasonablecost. Genetic sequencers use the application programming interface (API)of a file system. For network attached storage (NAS) the data are sentvia a network protocol like Network File System protocol (NFS) or ServerMessage Broadcast protocol (SMB) or other alternative protocols to storethe data in the NAS device using a file system internally. There areother application areas also generating very similar content to bestored in multiple files, for example applications recording, processingand storing seismic exploration data.

Some storage systems optimize storage capacity by eliminating identicalcopies of stored data. In some cases, stored data is divided intosegments. A new segment that is desired to be stored is first comparedagainst those segments already stored. If an identical segment isalready stored on the system, a reference to that segment is storedinstead of storing the new segment. This is referred to as identitycompression.

Despite increasing capacities of storage systems and network links,there are often benefits to reducing the size of file objects that arestored and/or transmitted. Examples of environments that would benefitinclude mobile devices with limited storage, communication overtelephone links, or storage of reference data, which is data that iswritten, saved permanently, and often never again accessed. Otherexamples include wide-area transfers of large objects, such asscientific data sets, or over saturated links. For example inself-contained storage systems, in which all data is stored in a singlelocation, data can take the form of files in a file system, objects in adatabase, or other storage device.

Numerous techniques for reducing large object sizes exist including datacompression, duplicate suppression, and delta encoding. Data compressionis the elimination of redundancy internally within an object. Duplicatesuppression is the process of eliminating redundancy caused by identicalobjects. Delta encoding or compression eliminates redundancy of anobject relative to another object, which may be an earlier version ofthe object having the same name. A delta compression method, forexample, optimizes storage capacity by comparing a new segment that isdesired to be stored against those segments already stored and lookingfor a similar though not necessarily identical segment. If a similarsegment is already stored on the system, a delta between the old and newsegment is computed and a reference to the old segment and the delta isstored in place of the entire new segment.

In US 2011/0196869 A1 a method for cluster storage is disclosed. Astorage system uses a cluster of nodes to store in-coming data.In-coming data is segmented. Each segment is characterized forassignment for storage on a given node. On the given node of thecluster, segments are stored in a manner that deduplicates segmentstorage.

Segments are deduplicated on each node of the cluster using deltacompression. Delta compression allows the use of large segments fordistributing efficiently to nodes so that sequential bytes are storedclose to each other on disk. Delta compression efficiently storessegments that are similar to each other by storing one base and, forother similar segments, storing only a delta from the base along with areference to the base. If a segment is not similar to a previouslystored base, the new segment is stored as a new base and possibly adelta from that base.

SUMMARY

In one illustrative embodiment, a method, in a data processing system,is provided for storing data files in a file system. In the illustrativeembodiment, the file system provides a plurality of reference data filesand each reference data file in the plurality of data files represents agroup of similar data files. The illustrative embodiment creates a newdata file. The illustrative embodiment associates the new data file withone reference data file in the plurality of data files thus defining anassociated reference data file of the plurality of reference data files.The illustrative embodiment informs the file system about theassociation of the new data file with the associated reference datafile. The illustrative embodiment compresses the new data file using theassociated reference data file thereby forming a compressed data file.The illustrative embodiment stores the compressed data file togetherwith information about the association of the new data file with theassociated reference data file.

In other illustrative embodiments, a computer program product comprisinga computer useable or readable medium having a computer readable programis provided. The computer readable program, when executed on a computingdevice, causes the computing device to perform various ones of, andcombinations of, the operations outlined above with regard to the methodillustrative embodiment.

In yet another illustrative embodiment, a system/apparatus is provided.The system/apparatus may comprise one or more processors and a memorycoupled to the one or more processors. The memory may compriseinstructions which, when executed by the one or more processors, causethe one or more processors to perform various ones of, and combinationsof, the operations outlined above with regard to the method illustrativeembodiment.

These and other features and advantages of the present invention will bedescribed in, or will become apparent to those of ordinary skill in theart in view of, the following detailed description of the exampleembodiments of the present invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The present invention together with the above-mentioned and otherobjects and advantages may best be understood from the followingdetailed description of the embodiments, but not restricted to theembodiments, wherein is shown in:

FIG. 1 depicts a system including a files association module and acompression module according to an example embodiment of the invention;

FIG. 2 depicts a file association and storage process according to anexample embodiment of the invention;

FIG. 3 depicts a delta compression process in a file system according toan example embodiment of the invention;

FIG. 4 depicts a file system structure depicting attributes for areference data file based compression method according to an exampleembodiment of the invention;

FIG. 5 depicts a file system with compressed data files maintaining alink to an associated reference data file according to an exampleembodiment of the invention;

FIG. 6 depicts a transliteration process for a compressed data file froma previous reference data file to a new reference data file according toa further example embodiment of the invention; and

FIG. 7 depicts an example embodiment of a data processing system forcarrying out a method according to the invention.

DETAILED DESCRIPTION

In the drawings, like elements are referred to with equal referencenumerals. The drawings are merely schematic representations, notintended to portray specific parameters of the invention. Moreover, thedrawings are intended to depict only typical embodiments of theinvention and therefore should not be considered as limiting the scopeof the invention.

For illustrating the invention, FIG. 1 depicts a system 100 including afile association module 36 and a compression module 32 according to anexample embodiment of the invention. The system 100 includes anapplication 30 running on a server 112, which on the other side iscoupled via a network 116 to a server 102, where a file system 10 isconfigured to run. The file system 10 represents a file orientedinterface to the application 30 such as a Network File System protocol(NFS) or a Server Message Broadcast protocol (SMB). The application 30generates and processes sets of similar data files. A file associationmodule 36 is integrated with the application 30 and is capable toanalyze the content of said data files. This enables the fileassociation module 36 to determine data files which are similar andgroup similar data files in groups or set of data files. This groupingcan also be based on rules given by the application 30 or the filesystem 10. For example one rule can be that all data files of a certaintype form one group. Another rule can be that all data files generatedin a specific period of time pertain to one set of files. For each setof similar data files the file association module 36 can nowautomatically generate a reference data file 12. Finally the fileassociation module 36 in conjunction with the application 30 stores adata file 14 in file system 10 via network 116 and thereby associatesthe data file 14 with said reference data file 12. A compression module32 as well as a decompression module 34 are integrated in the filesystem 10. According to the invention a data file 14 may be compressedusing the reference data file 12 to result in a compressed data file 16which may be stored afterwards. Details are described in the following.The decompression module 34 may on the other hand serve fordecompressing a compressed data file 16 using a reference data file 12in order to restore the original data file 14.

The file system 10 is connected to a storage device 106 comprising harddisk drives or other storage devices according to prior art. File system10 is the entity wherein files are being organized and stored on thestorage device 106. There might be multiple file systems storing fileson a single storage device 106 or a plurality of storage devices. A filesystem 10 contains an address space using names for the stored object,called name space. The file system 10, the servers 102, 112 and thestorage device 106 can also be one system. Also multiple servers 102,112 can build a cluster in scale out architecture. The file system 10may be part of an operation system running on a server or may run as afirmware on a controller.

One example for an implementation of the inventive method is describedbased on a file system crawler (a computer program that browses a filesystem in a methodical, automated manner or in an orderly fashion).Referring to FIG. 1, said file system crawler represents the application30 including the file association module 36. The file system crawleranalyzes data files stored in file system 10 in a directory structure.The file system 10 includes the compression module 32. Said file systemcrawler implements the following method to identify similar files,determine a reference data file for said similar data files andassociate said reference data file with said identified similar datafiles, denoted by the following steps: the file system crawler selects atype of files such as, for example, text files or presentation files orspread sheets; the file system crawler determines data files of saidselected file type stored in file system 10; among these files the filesystem crawler determines data files with similar content. This analysiscan be based on a text analysis of the file or an analysis of the filestructure. In one embodiment the file system crawler analyzes files witha similar file name stored in the same directory first. For saididentified similar data files the file system crawler determines thatpart of the contents which each of said similar data files contains andstores this part of the content in a new file representing a referencedata file. Said reference data file is also stored in file system 10.The file system crawler associates said similar data files with saidreference data file by instructing the compression module 32 of the filesystem 10. Based on this instruction the compression module 32 of thefile system 10 performs delta compression based on a prior art methodfor said similar data files using said reference data file.

Another example for an implementation of the inventive method is the useof storing genomic sequence data. The result of such scans is very largevolumes of data, in the order of 20 to 40 TBytes of data, representingseveral scans of genomic sequences where the information about theindividual is available, too. Such additional information can beutilized for associating reference data files based on the informationof an individual. As an example, known relationships between individualscan be used for associating the same reference data file to genomicsequences based on the assumptions that individuals with a closerelationship also share similar genomic sequences with a smaller set ofdifferences compared to unrelated individuals. Based on the knowledge ofrelationships the same reference data file can be associated to a set ofindividuals to store their genomic sequence data by using deltacompression. Due to the smaller amount of differences the deltacompression based on an appropriate reference data file the requiredstorage space is minimized. An example can be to use the genomicsequence data of a mother as the reference file for all children andgrandchildren. The determination of such relationships is based onassociated data about individuals providing genomic sequence data as ina patient data management system. Another use case is a set of genomicsequences being scanned from the same person. Differences in the genomicsequence, as created by viruses or mutations, are being stored as theresult of the delta compression algorithm for each scan based on onereference genomic sequence. This may also allow storing mutations of thegenomic sequence data over a longer period of time with just storing thedelta. The relationship between different genomic sequences is alsoknown by associated data being stored in a database containing theinformation about a patient like in a patient data management system.

For storing genomic sequence data based on delta compression the patientdata management system represented as application 30 may utilize thefile system 10 for storing genomic sequence data. Once an initialsequence data needs to be stored the application 30 determines thissequence as the reference data file as well. For any further data beingstored the file association module 36 determines whether the stored datahas a relationship to the previously stored reference data file. Thedetermination can vary based on the information being available in theapplication 30. If the relationship of individuals belonging to the samefamily can be determined all genomic sequence data of members of thisfamily can be associated with the reference data file being stored forthe first member. In the case of storing multiple genomic sequence datafor the same individual association can be done for the individual. Theassociation based on the file system namespace can be used here i.e. ifall data of the same individual is stored in the same directory. In thiscase the reference data file is associated by the file associationmodule 36 to the according directory. The file association module 36just needs to translate relationship into a directory structure beingprovided by the inventive system.

FIG. 2 explains a file association and storage process 800 according toan example embodiment of the invention. The process 800 may beimplemented in an application 30 and its embedded file associationmodule 36. After start of the process in step 802 the application 30generates similar data files 14 (FIG. 1) in step 804 and determines ifthere is a reference data file 12 (FIG. 1) for these similar data files14 in step 805 by examining rules which are configured. In step 806 ofthe process 800 it is checked if the reference data file 12 existsalready and if the answer is no the reference data file 12 will becreated in step 807. In step 808 the reference data file 12 is storedand the process 800 continues to step 810.

If the reference data file 12 already existed in step 806 then theprocess 800 flows to step 810 where the data files 14 generated in step804 are stored in the file system 10 (FIG. 1). In step 812 the process800 associates the data files 14 with the reference data file 12 bysending an instruction to the file system 10. For example thisinstruction can be based on an existing file link command including anew option (parameter) which instructs the file system 10 to associatethe reference data file 12 with the data file. Process 800 ends in step820.

The association of the reference data file 12 with the data file 14 canbe performed explicitly whereby the application instructs the filesystem 10 about this association (via file link command) or implicitlywhereby the reference data file 12 is associated with a sub-tree 28(FIGS. 4 and 5) of the file system 10 and the application stores saiddata files 14 in said sub-tree 28.

Reference data files may be created by one of the following steps, (i)comparing a plurality of data files 14 concerning at least one of a partof a file content, a file type, an origin of the plurality of data files14, (ii) determining similar data files in a file system 10 by a textanalysis of the data files 14 and/or an analysis of a file structure ofthe data files 14, (iii) determining similar data files 14 in a filesystem 10 by determining similarity in file names of the data files 14stored in a directory of the file system 10, (iv) determining a part ofcontents of said data files 14 being common to said data files 14, andfinally storing the part of contents in a new data file representing theassociated reference data file 12.

FIG. 3 explains a delta compression process 900 in a file system 10,which may follow the file association and storage process 800 accordingto an example embodiment of the invention. Once the data files 14 andreference data file 12 is stored in the file system 10 (see FIG. 1), forexample by the file association and storage process 800, the compressionmodule 32 performs the compression of said data files 14 according toprocess 900. The process 900 is implemented in file system 10 and itsembedded compression module 32. The process 900 starts in step 902 andcontinues to step 904 where the data files 14, the reference data file12 and the association instruction coming from process 800 (steps 810and 812 in FIG. 2) are received in the file system 10. In step 906 theprocess 900 determines the association of the data files 14 andreference data file 12 received in step 904 and determines in step 908whether the reference data file 12 exists in the file system 10. If thereference data file 12 does not exist in the file system 10 the process900 determines a default reference data file 12 in step 910. The defaultreference data file 12 can be set by an administrator of the file system10. The default reference data file 12 is thereby associated with asub-tree 28 of the file system 10, as shown in FIG. 5, in which the datafiles 14 are stored.

In step 912 the process 900 performs delta compression of said datafiles 14 according to prior art methods using said reference file 12 anda compression module 32 generating a delta compressed file 16 (FIG. 1).If both files contain very similar data this algorithm becomes effectiveand compression factors in a range between 90% to 99% becomesachievable. This information may be processed by a second prior artcompression algorithm, like a jpeg algorithm for example, forcompressing the delta information. Thus a further compression factor ofgreater than 1000 becomes realistic.

In step 914 the process 900 checks if the size of the delta compresseddata file 16 against a configurable size threshold and if the thresholdis exceeded the process 900 turns to step 916 where the delta compresseddata file 16 is decompressed to form the original data file 14, if itwas no longer available, using a decompression module 34. In step 918the original data file 14 is stored in the file system 10 and theprocess 900 ends in step 930.

If the size of the delta compressed file 16 is determined to be belowthe threshold in step 914 the process 900 turns to step 920 where theoriginal data file 14 is deleted and the delta compressed file 16 isstored in file system 10. Subsequently the process 900 stores theassociation information of the reference data file 12 in the deltacompressed file 16 in step 922. In an example embodiment thisinformation is stored in an inode (i.e. file structure information) ofthe delta compressed file 16. In an alternate embodiment thisinformation may be stored in the attributes of the delta compressed file16. The process 900 ends in step 930.

In one embodiment for large data files only a first portion of said datafile 14 is compressed in step 912 and then checked against the sizethreshold in step 914. If the size threshold is exceeded uponcompressing a first portion the original data file 14 is storeduncompressed in step 918. This embodiment allows to prevent resourceintensive compression of large data files which are not compressible.

From a user or application 30 perspective the file system 10 presentsthe data files as original data files 14 even though the original datafile 14 is compressed. This can be achieved naming the delta compresseddata file 16 the same as the original data file 14 and showing the sameattributes (especially size) through the interface of the file system10.

In step 908 of process 900 in FIG. 3 the existence of a reference datafile 12 associated with one or more data files 14 is checked and ifthere is no reference data file 12 associated with data files 14 or thereference data file 12 is not available the process 900 introduces theconcept of a default reference file 12. Thereby the administrator of thefile system 10 can associate reference data files 12 with directories orpartitions of the file system 10. In step 910 of process 900 thisassociation is checked. In FIG. 4 a concept of a static association ofreference data files with file system directories or partitions isexplained.

FIG. 4 shows a file system structure depicting attributes for areference data file based compression method according to an exampleembodiment of the invention. FIG. 4 therefore shows a file system 10,within server 102, containing entities (directories or partitions) forsubdividing the namespace and files. It divides the namespace in moremanageable units allowing to apply attributes being used for rules ondata file placements or other types of attributes. A sub-tree 28 of filesystem 10, file set 18 b, has an associated attribute 40 including anassociation with a reference data file 12 and an attribute 42associating a compression module 32. Once these attributes 40, 42 areassociated to the file set 18 b all data files being written into thisfile set 18 b are interpreted as data files to be delta compressed usingthe compression module 32 associated by attribute 42 and the referencedata file 12 associated by attribute 40. In addition, all data files inthe remaining namespace of the file system 10, such as data files 18 a,20 a, 22 a-d, will be stored without any compression according to theexample embodiment in FIG. 4. While the example just shows theassociation to a file set 18 b the attributes can also be associated tothe file system 10, or to directories or subdirectories 20 a, 20 b, 20c, . . . .

FIG. 5 depicts a file system 10 with compressed data files maintaining alink to an associated reference data file according to an exampleembodiment of the invention, as a part of the inventive methodconcerning static association of reference data files based onnamespaces. FIG. 5 therefore shows the contents of a file system 10,within server 102, with an association of the attributes 40 and 42 to asub-tree 28 of file system 10, file set 18 b like in FIG. 4. After theassociation new data files are created and written to the file system 10within the directory 20 a. The directory 20 a contained already a file16 a. Now a new data file 16 b is created in the directory 20 a. Thedata being written into this data file 16 b are processed by the deltacompression module 32 referenced in attribute 42 based on the referencedata file 12 referenced in attribute 40. For keeping the relationshipthe delta compressed data file 16 b maintains a link 44 to the referencedata file of attribute 40. In file systems this relationship isrepresented within an inode (i.e. file structure information) ofreference data file of attribute 40 in an inode of file 16 b. Files 16c, 16 d, and 16 e are created and written later on in the same way.Assuming the data being written to files 16 b, 16 c, 16 d, and 16 e hada correlation like to genomes from two individuals the amount of storeddata in these data files is significantly smaller.

Delta compressed data files 16 can also be re-associated with newreference data files 24 whereby the compression of these data files 16will be performed using a new reference data file 24, as is shown inFIG. 6. This can be done explicitly whereby the application 30 instructsthe file system 10 with its compression module 32 to associate a givendata file 16 with a new reference data file 24 (for example via a filelink command). Or this can be done implicitly whereby a compressed datafile 16 is copied from one directory to another directory within thefiles system 10 and the new directory is associated with a differentreference data file 24.

FIG. 6 explains this so-called transliteration process for a compresseddata file 16, within files system 10, from a previous reference datafile 12 to a new reference data file 24 according to a further exampleembodiment of the invention. The transliteration of a delta compressedfile 16 is carried out by a decompression module 34 for extracting anuncompressed previous data file 14. In a second step of data processingthe compression module 32 takes the file 14 as input and the data file24 as the new reference data file. After processing the data files a newdelta compressed data file 26 is being stored. The file 14 is storedtemporarily. Alternatively, the output of the decompression module 34 istaken directly as the input of the compression module 32, not beingstored in a file at all.

There are the following scenarios of handling an inheritance, i.e. arelationship to the correct associated reference data file, in detail:

Scenario 1: A data file 16 is copied or moved from one part of thenamespace in a file system 10 into another one i.e. from one directoryto another one. If different reference data files are associated to thesource and target directory the data file is transliterated by the moveoperation as file 26. If contents of the file 16 are moved to file 26the file 16 gets deleted. For a copy operation the file 16 is remainingunchanged.

Scenario 2: A delta compressed file 16 is copied or moved into anotherpart of the namespace i.e. from one directory into another one. If thetarget directory has no associated reference data file the deltacompressed file 16 needs to be decompressed and being stored in theoriginal format. Depending on whether a copy or move operation iscarried out the file 16 gets deleted or not.

Scenario 3: A new reference data file 24 is associated to a part of thenamespace i.e. a directory. All delta compressed data files 16 beingstored in this directory need to be transliterated to use the newreference data file 24.

Scenario 4: A reference data file 12 is being deleted. All deltacompressed data files 16 being associated to this part of the namespaceare decompressed into their original data file 14.

Access to delta compressed data file 16 might be accomplished by thefollowing way. Next to saving space on the storage device 106 being usedby the data files 16, a delta information of a data file 16 based on areference data file 12 can be used for computations itself. The data canbe made accessible by just decompressing the delta compressed data file16. Depending on the capabilities of the file system API an application30 might access the delta information as an alternate data stream orunder a different file name.

Referring now to FIG. 7, a schematic of an example of a data processingsystem 210 is shown. Data processing system 210 is only one example of asuitable data processing system and is not intended to suggest anylimitation as to the scope of use or functionality of embodiments of theinvention described herein. Regardless, data processing system 210 iscapable of being implemented and/or performing any of the functionalityset forth herein above.

In data processing system 210 there is a computer system/server 212,which is operational with numerous other general purpose or specialpurpose computing system environments or configurations. Examples ofwell-known computing systems, environments, and/or configurations thatmay be suitable for use with computer system/server 212 include, but arenot limited to, personal computer systems, server computer systems, thinclients, thick clients, handheld or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices, and the like.

Computer system/server 212 may be described in the general context ofcomputer system executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 212 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 7, computer system/server 212 in data processing system210 is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 212 may include, but are notlimited to, one or more processors or processing units 216, a systemmemory 228, and a bus 218 that couples various system componentsincluding system memory 228 to processor 216.

Bus 218 represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, and notlimitation, such architectures include Industry Standard Architecture(ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA)bus, Video Electronics Standards Association (VESA) local bus, andPeripheral Component Interconnect (PCI) bus.

Computer system/server 212 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 212, and it includes both volatileand non-volatile media, removable and non-removable media.

System memory 228 can include computer system readable media in the formof volatile memory, such as random access memory (RAM) 230 and/or cachememory 232. Computer system/server 212 may further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 234 can be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a “hard drive”). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus 218 by one or more datamedia interfaces. As will be further depicted and described below,memory 228 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of embodiments of the invention.

Storage system 234 may also exhibit interfaces for separate storagemedia for the reference data files 12 than for the data files 14 and/orthe compressed data files 16, as these reference data files 12 are thebasis for a plurality of compressed data files 16 and may therefore bestored on separate storage media. Also the reference data files 12 maybe backed up on separate backup media than the data files 14 and/or thecompressed data files 16 as well as may be backed up on separate and/ormultiple backup media of special performance and reliability.

Program/utility 240, having a set (at least one) of program modules 242,may be stored in memory 228 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 242 generally carry out the functionsand/or methodologies of embodiments of the invention as describedherein. Computer system/server 212 may also communicate with one or moreexternal devices 214 such as a keyboard, a pointing device, a display224, etc.; one or more devices that enable a user to interact withcomputer system/server 212; and/or any devices (e.g., network card,modem, etc.) that enable computer system/server 212 to communicate withone or more other computing devices. Such communication can occur viaInput/Output (I/O) interfaces 222. Still yet, computer system/server 212can communicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 220. As depicted, network adapter 220communicates with the other components of computer system/server 212 viabus 218. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 212. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

The block diagrams in the figures illustrate the architecture,functionality, and operation of possible implementations of systems,methods and computer program products according to various embodimentsof the present invention. In this regard, each block in the blockdiagrams may represent a module, segment, or portion of code, whichcomprises one or more executable instructions for implementing thespecified logical functions. It should also be noted that, in somealternative implementations, the functions noted in the block may occurout of the order noted in the figures. For example, two blocks shown insuccession may, in fact, be executed substantially concurrently, or theblocks may sometimes be executed in the reverse order, depending uponthe functionality involved. It will also be noted that each block of theblock diagrams, and combinations of blocks in the block diagrams, can beimplemented by special purpose hardware-based systems that perform thespecified functions or acts, or combinations of special purpose hardwareand computer instructions.

As will be appreciated by one skilled in the art, aspects of the presentinvention may be embodied as a system, method or computer programproduct. Accordingly, aspects of the present invention may take the formof an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”

Furthermore, aspects of the present invention may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Rash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device. A computer readable signal medium may include apropagated data signal with computer readable program code embodiedtherein, for example, in baseband or as part of a carrier wave. Such apropagated signal may take any of a variety of forms, including, but notlimited to, electro-magnetic, optical, or any suitable combinationthereof. A computer readable signal medium may be any computer readablemedium that is not a computer readable storage medium and that cancommunicate, propagate, or transport a program for use by or inconnection with an instruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent invention may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

Aspects of the present invention are described below with reference toblock diagrams of methods, apparatus (systems) and computer programproducts according to embodiments of the invention. It will beunderstood that each block of the flowchart illustrations and/or blockdiagrams, and combinations of blocks in the block diagrams, can beimplemented by computer program instructions. These computer programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the block diagram block orblocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the block diagram block orblocks.

1. A method, in a data processing system, for storing data files in afile system, wherein the file system provides a plurality of referencedata files, wherein each reference data file in the plurality of datafiles represents a group of similar data files, the method comprising:creating a new data file; associating the new data file with onereference data file in the plurality of data files thus defining anassociated reference data file of the plurality of reference data files;informing the file system about the association of the new data filewith the associated reference data file; compressing the new data fileusing the associated reference data file thereby forming a compresseddata file; and storing the compressed data file together withinformation about the association of the new data file with theassociated reference data file.
 2. The method according to claim 1,wherein the reference data file is created by the method comprising:comparing a plurality of data files concerning at least one of a part ofa file content, a file type, an origin of the plurality of data files;determining a part of contents of the plurality of data files beingcommon to the plurality of data files; and storing the part of contentsin reference data file.
 3. The method according to claim 1, wherein thereference data file is created by the method comprising: determiningsimilar data files in the file system by a text analysis of the datafiles or an analysis of a file structure of the data files; determininga part of contents of the data files being common to the data files; andstoring the part of contents in the reference data file.
 4. The methodaccording to claim 1, wherein the reference data file is created by themethod comprising: determining similar data files in the file system bydetermining a similarity in file names of the data files stored in adirectory of the file system; determining a part of contents of the datafiles being common to the data files; and storing the part of contentsin the reference data file.
 5. The method according to claim 1, whereinthe new data file is associated with the one reference data file by themethod comprising: responsive to no reference data file existing to thedata in the new data file, generating the associated reference data filefor the new data file to be stored in the file system; responsive to theone reference data file existing to the data in the new data file,selecting the one reference data file as the associated reference datafile for the new data file to be stored in the file system; storing theassociated reference data file and the new data file in the file system;and informing the file system about the association of the new data filewith the associated reference data file.
 6. The method according toclaim 1, wherein associating the new data file with the one referencedata file is performed by the method comprising: associating theassociated reference data file with a sub-tree of the file system; andstoring the new data file in the sub-tree.
 7. The method according toclaim 1, wherein informing the file system about the association of thenew data file with the associated reference data file is performed by afile link command.
 8. The method according to claim 1, wherein the newdata file is compressed by the method comprising: receiving the new datafile from an application; if information in the new data file indicatesthat the new data file can be associated with an existing reference datafile, determining the existing reference data file as the associatedreference data file; if the information in the new data file indicatesthat the new data file cannot be associated with an existing referencedata file, associating the new data file with a default reference datafile as the associated reference data file; compressing the new datafile using the associated reference data file thereby forming acompressed data file; providing a comparison result about a size of thecompressed data file to a size of the uncompressed data file; anddeciding on storing the compressed data file or the uncompressed datafile depending on the comparison result.
 9. The method according toclaim 1, wherein compressing the new data file is performed by a deltacompressing method.
 10. The method according to claim 1, whereintransliteration of the compressed data file associated with a previousassociated reference data file with a new associated reference data fileis performed by the method comprising: decompressing the compressed datafile using the previous associated reference data file thereby creatinga previous data file; and compressing the previous data file using thenew associated reference data file thereby forming a new compressed datafile; and storing the information about the new associated referencedata file with the new compressed data file.
 11. The method according toclaim 10, further comprising: identifying a set of compressed data filesin the file system being compressed with the previous associatedreference data file; decompressing the set of compressed data filesusing the previous associated reference data file thereby creating, foreach compressed data file in the set of compressed data files, aprevious data file thereby forming a set of previous data files;compressing each of the set of previous data files using the newassociated reference data file thereby forming a set of new compresseddata files; providing, for each of the new compressed data files, acomparison result about a size of the previous data file beingcompressed with the new associated reference data file to a size of theprevious data file being compressed with the previous associatedreference data file; and deciding for each of the new compressed datafiles on storing being compressed with the new associated reference datafile or with the previous associated reference data file.
 12. The methodaccording to claim 1, wherein the plurality of reference data files arestored on a separate computer readable storage medium than the datafiles or the compressed data files.
 13. (canceled)
 14. A computerprogram product comprising a computer readable storage medium having acomputer readable program stored therein, wherein the computer readableprogram, when executed on a computing device, causes the computingdevice to: create a new data file; associate the new data file with onereference data file in a plurality of data files thus defining anassociated reference data file of a plurality of reference data files;inform a file system about the association of the new data file with theassociated reference data file; compress the new data file using theassociated reference data file thereby forming a compressed data file;and store the compressed data file together with information about theassociation of the new data file with the associated reference datafile.
 15. A data processing system comprising: a processor; and a memorycoupled to the processor, wherein the memory comprises instructionswhich, when executed by the processor, cause the processor to: create anew data file; associate the new data file with one reference data filein a plurality of data files thus defining an associated reference datafile of a plurality of reference data files; inform a file system aboutthe association of the new data file with the associated reference datafile; compress the new data file using the associated reference datafile thereby forming a compressed data file; and store the compresseddata file together with information about the association of the newdata file with the associated reference data file.
 16. The dataprocessing system according to claim 15, wherein the reference data fileis created by the instructions further causing the processor to: comparea plurality of data files concerning at least one of a part of a filecontent, a file type, an origin of the plurality of data files;determine a part of contents of the plurality of data files being commonto the plurality of data files; and store the part of contents in thereference data file.
 17. The data processing system according to claim15, wherein the reference data file is created by the instructionsfurther causing the processor to: determine similar data files in thefile system by a text analysis of the data files or an analysis of afile structure of the data files; determine a part of contents of thedata files being common to the data files; and store the part ofcontents in the reference data file.
 18. The data processing systemaccording to claim 15, wherein the reference data file is created by theinstructions further causing the processor to: determine similar datafiles in the file system by determining a similarity in file names ofthe data files stored in a directory of the file system; determine apart of contents of the data files being common to the data files; andstore the part of contents in the reference data file.
 19. The dataprocessing system according to claim 15, wherein the new data file isassociated with the one reference data file by the instructions furthercausing the processor to: responsive to no reference data file existingto the data in the new data file, generate the associated reference datafile for the new data file to be stored in the file system; responsiveto the one reference data file existing to the data in the new datafile, select the one reference data file as the associated referencedata file for the new data file to be stored in the file system; storethe associated reference data file and the new data file in the filesystem; and inform the file system about the association of the new datafile with the associated reference data file.
 20. The data processingsystem according to claim 15, wherein associating the new data file withthe one reference data file is performed by the instructions furthercausing the processor to: associate the associated reference data filewith a sub-tree of the file system; and store the new data file in thesub-tree.
 21. The data processing system according to claim 15, whereinthe new data file is compressed by the instructions further causing theprocessor to: receive the new data file from an application; ifinformation in the new data file indicates that the new data file can beassociated with an existing reference data file, determine the existingreference data file as the associated reference data file; if theinformation in the new data file indicates that the new data file cannotbe associated with an existing reference data file, associate the newdata file with a default reference data file as the associated referencedata file; compress the new data file using the associated referencedata file thereby forming a compressed data file; provide a comparisonresult about a size of the compressed data file to a size of theuncompressed data file; and decide on storing the compressed data fileor the uncompressed data file depending on the comparison result.